Alkali or alkaline earth metal promoted catalyst and a process for methanol synthesis using alkali or alkaline earth metals as promoters

ABSTRACT

The present invention relates to a novel route for the synthesis of methanol, and more specifically to the production of methanol by contacting synthesis gas under relatively mild conditions in a slurry phase with a heterogeneous catalyst comprising reduced copper chromite impregnated with an alkali or alkaline earth metal. There is thus no need to add a separate alkali or alkaline earth compound. The present invention allows the synthesis of methanol to occur in the temperature range of approximately 100°-160° C. and the pressure range of 40-65 atm. The process produces methanol with up to 90% syngas conversion per pass and up to 95% methanol selectivity. The only major by-product is a small amount of easily separated methyl formate. Very small amounts of water, carbon dioxide and dimethyl ether are also produced. The present catalyst combination also is capable of tolerating fluctuations in the H 2  /CO ratio without major deleterious effect on the reaction rate. Furthermore, carbon dioxide and water are also tolerated without substantial catalyst deactivation.

The subject invention was made in part with Government support underSubcontract No. DE-FG22-89PC89786 awarded by the Department of Energy.The Government has certain rights in this invention.

This is a continuation of copending application Ser. No. 07/823,127filed on Jan. 21, 1992 which is a division of Ser. No. 07/675,140, filedMar. 26, 1991, both of which are abandoned.

FIELD OF THE INVENTION

The present invention relates to a novel route for synthesizingmethanol. Specifically the invention relates to the production ofmethanol using a heterogeneous catalyst comprising a copper chromiteupon which an alkali or alkaline earth metal has been impregnated.

BACKGROUND OF THE INVENTION

Hydrocarbon mixtures such as gasoline and more recently diesel and jetfuels have served as transportation fuels for many years. Recent socialand environmental concerns, particularly with respect to NO_(x) andhydrocarbon gas emissions, however, have led to growing demand foralternate, cleaner burning fuels. Similarly, erosion of the ozone layerin the atmosphere and acid rain have led to a strong demand forcontrolled atmospheric emissions.

In this context, fuel oxygenates, particularly alcohols have emerged asstrong contenders in the quest to develop cleaner burning fuels.Methanol is the cheapest and the most abundant of these alcohols.Favorable factors of methanol include its high octane rating, itsmanufacture from abundant natural resources (e.g. coal, gas, petroleumfractions, residual biomass and other agricultural products) and itsability to lessen environmental damage.

The current U.S. consumption of methanol is 1.3 billion gallons/yr.,while the current U.S. gasoline consumption is 122 billion gallons/yr.Thus, it is likely that methanol will become a very important motor fuelor motor fuel supplement in the future.

Moreover, methanol can undergo a variety of reactions, some because ofthe presence of the hydroxide group, others because of the absence ofsteric hindrance of the methyl group, and still others because the --CH₂OH group is bound to the hydrogen atom rather than to another carbonatom. Methanol is, therefore, an important chemical precursor. It iswidely used in the manufacture of formaldehyde (20% of totalconsumption), chloromethanes, acetic acid, methyl acetate and methylformate. It is also used as an intermediate in the manufacture of aceticanhydride and in the manufacture of dimethyl ether. Methanol also findsincreasing use as an octane booster for gasoline by direct blending oras a raw material for methyl tert-butyl ether (MTBE) and for fuel cellapplications. Furthermore, there is the exciting discovery that methanolcan be converted to high octane gasoline by the Mobilmethanol-to-gasoline (MTG) process.

Methanol is currently produced almost solely by reacting synthesis gas("syngas") comprising hydrogen and carbon monoxide in the presence of aheterogeneous copper catalyst. Methanol was first produced from syngasby Badische Anilin & Soda-Fabrik AG, Germany in 1923, according to thereaction shown in the following equation:

    2H.sub.2 +CO→CH.sub.30 H

Zinc/chromium oxide catalyst was used, with a high selectivity forformation of methanol at temperatures between 320 and 380° C., andpressures of 300 to 350 atm. This catalyst along with minor variants wasused in the "high pressure" methanol synthesis up to the mid 1960's. Thereaction such as described in the above equation, in which methanol isproduced from synthesis gas in one step, is often referred to as the"direct synthesis."

In 1966, a new "low pressure" process was developed by The ImperialChemical Industries ("ICI"). This process uses Cu/ZnO or Cu/ZnO/Al₂ O₃as a catalyst and operates at 200°-300° C. and 50-110 atm. Today, mostmethanol is manufactured by this method. The reaction is carried out inthe gas phase in a fixed bed reactor. Approximately 6% by volume of CO₂is normally added to the syngas feed. It has been reported that all themethanol is formed via CO₂ rather than CO as discussed by G. C.Chinchen, et al. in Chemtech, 692 (November 1990).

The power requirements, good catalyst life, larger capacity single-trainconvertor designs and improved reliability, of the low pressuretechnology result in lower energy consumption and economy of scale.However, the low pressure direct process has certain drawbacks. Chiefamong these drawbacks is the high operating temperature (T=250° C.).Thermodynamic calculations show that, at a temperature of 250° C. and apressure of 50 atm, 51.9% of the syngas can be converted at equilibrium.These calculations are based upon a stoichiometric H₂ /CO feedcomposition of 2 and an assumption of ideal gases. Under presentindustrial conditions, however, only about 6-12% conversion per pass istypically achieved.

The methanol synthesis reaction is very exothermic. Poor heat transferin the catalyst bed results in an outlet methanol concentration limitedto 5-6 mole%. Either cool unreacted gas injected at stages in thecatalyst bed or internal cooling surfaces is generally used to controlthe bed temperature. To achieve maximum conversion of the carbon oxides,an excess of H₂ is used. The excess of H₂ requires a high recycle ratiowhich, in turn, leads to greater expense. Therefore, any modification inthe process technology that can enhance heat transfer will result inhigher conversions. Furthermore, a decrease in operating temperaturecould result in lower energy consumption and a higher equilibriumconversion.

To overcome the heat transfer limitation, slurry phase processes arebeing developed. Processes based on three phase fluidized bed, threephase fixed bed, slurry phase bubble column and mechanically agitatedslurry phase reactors are known. These processes take advantage of theoutstanding characteristics of a slurry reactor; notably the excellentheat transfer between the catalyst and the liquid, with the liquidserving as a heat sink for the heat of reaction. The use of slurryreactors results in excellent temperature control and higher synthesisgas conversion per pass. These processes, though not yet commercialized,operate at almost the same temperature and pressure as the gas phaseprocess.

A process based on slurry phase technology is the "LaPorte process"being jointly developed by Air Products and Chem Systems (D. M. Brownand M. I. Greene, "Catalyst Performance in Liquid Phase MethanolSynthesis", presented at the Summer National AICLE Meeting,Philadelphia, August 1984). This process has been claimed to be nearcommercialization. The process development unit incorporates anebullated slurry bubble column capable of once-through operation onclean coal gasifier effluent gas. The catalyst, which is suspended inthe liquid phase, is a Cu/ZnO catalyst. Higher synthesis gas conversionsper pass than achieved in gas-phase processes have been reported for theLaPorte process. The use of coal derived synthesis gas which is rich inCO has been reported to yield no substantial difference in the rate ofmethanol synthesis.

Although the use of slurry reactors provides beneficial results, severalproblems persist with the current "low pressure" technology. Mostimportantly, the synthesis temperature is still quite high. Becauselower reaction temperatures result in lower free energy change for thereaction, the production of methanol is unfavorable at hightemperatures. Temperatures of 240 to 260° C. and high pressures areneeded to achieve high reaction rates with the currently used processtechnology. Therefore, if catalysts with higher activity at lowertemperatures could be developed, considerable improvement in theeconomics of the process would result.

A promising, but little studied, alternate route is a "two-step"synthesis to methanol via methyl formate disclosed in U.S. Pat. No.1,302,011. The two-step synthesis comprises the carbonylation of acarrier alcohol to the corresponding alcohol formate using alkalialkoxides as homogeneous catalysts. The carbonylation step is followedby hydrogenolysis of the formate on the surface of copper chromite toyield the carrier alcohol and MeOH. The reaction sequence is shown bythe following equations:

Carbonylation of carrier alcohol,

    ROH+CO→HCOOR

Hydrogenolysis of the corresponding formate,

    ROOCH+2H.sub.2 →CH.sub.30 H+ROH

The two individual reactions are well known, the former being thecommercial route to methyl formate production. The carbonylationreaction is carried out at temperatures of 80°-100° C. and pressures of30-50 atm in the presence of a homogeneous catalyst. The carbonylationreaction thus takes place in the liquid phase. The hydrogenolysis ofmethyl formate can be carried out at temperatures of 100°-160° C. andatmospheric pressure in the presence of a heterogeneous catalyst.Carrying out these two steps in series can result in methanol synthesisat considerably milder conditions. If the carrier alcohol used is MeOH,the reaction yields two moles of MeOH as product. Reaction ratescomparable to those obtained commercially and reduced separation costsare obtained by using methanol as the carrier alcohol.

The two-step process has several advantages over the direct methanolsynthesis technology, including: lower reaction temperatures; highersynthesis gas conversions per pass, thus decreasing recycle load; andimproved heat transfer, because the reaction is carried out in a liquidslurry.

The two-step synthesis process via alkyl formate avoids thethermodynamic limitations of presently practiced methanol synthesis,making the process less energy intensive. The liquid phase acts as aheat sink reducing the heat transfer limitation. When methanol is usedas a solvent, mass transfer limitations are reduced. This process thusprovides an efficient route to the manufacture of methanol.

A major disadvantage of the two-step process, however, is the need fortwo reactor systems and two feed preparation systems. A seeminglyattractive alternative would be to carry out both reactions concurrentlyin the same reactor ("concurrent synthesis"). It is not clear, however,that such a combination of reactions would be feasible. Viewedindependently, the carbonylation and hydrogenolysis reactions appear tobe incompatible.

Initially, CO, one of the reactants in the carbonylation reaction,inhibits the hydrogenolysis reaction. Furthermore, CO₂, which is usuallypresent in syngas, has a strong negative effect on both reactions. Thenegative effect of CO₂ in the carbonylation reaction appears to beirreversible when the CO₂ is removed. Finally, selection of an operatingtemperature must be a compromise between the relatively low temperaturerequired to obtain high conversion in the carbonylation reaction and thehigher temperature required to obtain a reasonable rate in thehydrogenolysis reaction.

Experimental evidence showing that the carbonylation and hydrogenolysisreactions can occur in a single reactor containing sodium methoxide(NaOMe) at 200° C. and 150-250 atm. and copper-chromium-calcium catalystwas provided by Imyanitov, N. B., et al., in Gidroformilirovanie, 152(1972). Evidence showing that the concurrent reaction can occur at 200°C. and 150-250 atm. with sodium carbonate or sodium formate incombination with a copper-chromium-calcium catalyst was also provided.

Aker Engineering, in Petrole Informations, May 13, 1982, also reported atwo-component liquid phase catalytic system to convert syngas to amixture of methanol and methyl formate in a single reactor. The processwas reported to operate typically at 110° C. and 0.5 MPa. Under theseconditions the main product would be methylformate rather than methanol.The report disclosed the use of only alkali and/or alkaline earthalkoxides (alcoholates) as the carbonylation catalyst with copperchromite as the hydrogenolysis catalyst. The report also emphasized,however, the need to eliminate all CO₂, H₂ O and sulfur compounds fromthe inlet syngas.

Similarly, U.S. Pat. No. 4,731,386 discloses preparation of methanolfrom syngas in a liquid reaction mixture in the presence of a catalystsystem consisting of an alkali alcoholate and a heterogeneous coppercatalyst. It was found that the addition of a non-polar organic solventhaving weak cation solvatizing properties in the liquid phase, otherwiseconsisting of methanol and methylformate, substantially increased thecatalytic activity of catalyst systems consisting of an alkali metal.alcoholate and a heterogeneous copper catalyst.

Liu, Z., et al., "Methanol Synthesis via Methyl Formate in a SlurryReactor", 18 Fuel Processing Technology, 185 (1988), studied concurrentsynthesis in a slurry reaction using KOCH₃ and a copper chromite attemperatures of 140°-180° C. and pressures of 3.8-6.2 MPa. Liu, et al.found the results from the concurrent methanol synthesis to be differentfrom those predicted by the individual reactions. Methanol productionwas found to be higher and the effect of CO₂ was lessened andreversible. A "small" amount of water was reported not to be detrimentalto catalyst activity. Rates of reaction were found to be comparable tothose reported for direct synthesis.

It is thus known that methoxides such as those derived from sodium orpotassium or alkaline earth metals such as barium can be used along witha copper chromite catalyst in the concurrent synthesis of methanol. Themain drawback of using a catalyst system including methoxides is thehigh cost required for catalyst manufacture and activity upkeep.Carbonates and formates have similarly been used in the concurrentprocess, but only at highly elevated temperatures.

The high temperatures currently needed to synthesize methanol via thedirect route using copper-zinc catalysts and the high cost of usingmethoxides as a catalyst make it highly desirable to develop inexpensivealternative catalyst systems which enable methanol synthesis under mildtemperatures while achieving high syngas conversion per pass and highmethanol selectivity.

SUMMARY OF THE INVENTION

The present invention relates to a novel route for the synthesis ofmethanol, and more specifically, to the production of methanol bycontacting a gaseous mixture of carbon monoxide and hydrogen underrelatively mild conditions in a slurry phase, with a heterogeneouscatalyst comprising reduced copper chromite upon which an alkali metalor alkaline earth has been impregnated. Heterogeneous catalysis refersto a reaction in which two or more phases are involved. Any convenientsource of the alkali metal or alkaline earth metals such as the oxide,nitrate, hydroxide, carbonate, bicarbonate, formate, citrate, oxalate,acetate, or butyrate can be used. Generally, any water-soluble alkalimetal compound or alkaline metal compound is suitable. Preferably, thecarbonate or the nitrate is used. The alkali could be lithium, sodium,potassium, rubidium or cesium, and the alkaline earth metal could bemagnesium, calcium, strontium or barium. The addition of an alkali oralkaline earth compound as a separate salt is totally eliminated. Theprocess produces methanol with up to 90% syngas conversion per pass andup to 95% methanol selectivity. The only major by-products are smallamounts of easily separated methyl formate and very small amounts ofwater, carbon dioxide and dimethyl ether.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

The present invention relates to a novel route for the synthesis ofmethanol from syngas using a catalyst comprising a heterogeneous copperchromite upon which an alkali or alkaline earth metal has beenimpregnated. (Impregnation is also referred to as "decoration" or"doping"). Materials impregnated upon catalysts to enhance catalyticactivity are commonly known as promoters.

Suitable alkali metals include lithium, sodium, potassium, rubidium andcesium. Preferably, sodium, potassium, rubidium or cesium compounds areused. Suitable alkaline earth metals include magnesium, calcium andbarium. Preferably, calcium or barium compounds are used.

The catalyst system of the present process has the ability to toleratefluctuations in the H₂ :CO ratio without having a major deleteriouseffect on the reaction rate. Almost no change in the reaction rate isobserved in the H₂ :CO ratio range of 1.5-2.0:1. The present synthesisroute thus enables the use of a wide range of H₂ :CO ratios. The H₂ :COratio can range from 0.5:1 to 3:1. Preferably, the H₂ :CO ratio rangesfrom 1:1 to 3:1. Most preferably, a stoichiometric ratio of 2:1 is used.

Moreover, carbon dioxide in the inlet gas can also be tolerated.Experiments with an inlet gas composition of 0.1-0.3% have been runsuccessfully. However, up to 6% CO₂ has been generated during thereaction startup. The system has the ability to simultaneously toleratethis level of CO₂ and to self-stabilize itself in terms of the CO₂level. Furthermore, a steady-state outlet concentration of 0.8% iseasily tolerated.

Similarly, the presence of water can also be tolerated by the presentcatalyst system. A steady-state water concentration of 0.2-0.3% in theliquid phase does not seriously affect the reaction rate. Water isalways present in the liquid phase because of the water-gas shiftreaction. The water concentration can be kept within the acceptablerange by controlling the water-gas shift reaction. However, it ispreferable that the reactants be as dry as possible.

The copper content of the copper chromite catalyst is preferably in therange of approximately 30% to 60%. The chromium content of the copperchromite catalyst is preferably in the range of approximately 40% to60%. The reaction can be carried out in a continuous or semi-continuousmanner at temperatures between approximately 100°-160° C., and pressuresbetween approximately 40-65 atm. The feed velocity at which the processis carried out is preferably in the range of 60-140 cc./min. based on aliquid reactor volume of 150 cc, these values being measured atconditions of standard pressure and temperature.

Preferably, methanol is used as the carrier alcohol. Although otheralcohols, such as ethanol, propanol and higher alcohols can be used asthe carrier alcohol, their use may result in undesirable side productsand could complicate product recovery.

Because the alkali or alkaline earth enhances the activity of the copperchromite catalyst , the reduced form of this catalyst combination, whenreacted with methanol, produces methanol with up to 90% syngasconversion and up to 95% methanol selectivity. Syngas conversions of 95%or more should be easily obtainable when operated in a continuousmanner. The high per pass conversion of syngas eliminates or greatlyreduces the necessity of recycle. The syngas conversion and methanolselectivity obtained with the present catalyst systems are comparable tothose currently achieved by the industrial synthesis of methanol attemperatures of approximately 50° C.

The major by-product of this reaction is a small amount of highlyvolatile, but easily separated, methyl formate. Other by-productsinclude water, CO₂ and dimethyl ether, all in considerably smallerquantities. Other oxygenated products or higher alcohols are produced,at most, in trace quantities.

Low deactivation rates were obtained with the present alkali or alkalineearth promoted catalysts, thus ensuring catalyst activity. The reducedform of the present catalyst combination, when reacted with methanol,therefore, provides a novel cost efficient route to the synthesis ofmethanol.

The copper chromite catalyst used in the present heterogeneous catalystcan be prepared by a number of techniques. One such technique forpreparation of promoted catalysts is the incipient wetness technique.The incipient wetness technique is described in detail in Satterfield,C. N., Heterogeneous Catalyst in Practice, McGraw-Hill Book Company, NewYork (1980) and Richardson, J. T., Principles of Catalyst Development,Plenum Press, New York (1989). The incipient wetness technique was usedfor impregnating alkali metals or alkaline earth metals onto the surfaceof copper chromite in preparation of alkali metal decorated copperchromite.

In preparation of the alkali or alkaline earth promoted copper chromitecatalyst using the incipient wetness technique, it was first determinedthat 1.3 ml of H₂ O was needed to just wet the surface (incipientwetness) of 2 gm of copper chromite. Therefore, 6.5 ml of water would beneeded to just wet the surface of 10 gm copper chromite.

In preparation of a typical 10 gm supply of decorated copper chromitecatalyst impregnated with x gms. of alkali metal or alkaline earth metalcompound, an overall 3-step process was generally used. Initially, 10 gmof copper chromite was weighed and x/3 gm of alkali salt (e.g. K₂ CO₃ orCs₂ CO₃) dissolved in 6.5 ml of water was added to the copper chromitewith constant stirring. The solution just wets the surface of the copperchromite. The wetted powder was stirred continually for 5-10 minutes toachieve good dispersion. It was then dried in an oven at 110° C. for twohours. The addition of x/3 gm of alkali salt in 6.5 ml of water and thelatter steps were repeated two more time to impregnate x gm of alkalimetal compound or alkaline earth metal compound on the surface of thecopper chromite. The catalyst resulting from this impregnation techniqueis referred to as an alkali promoted (or decorated or impregnated ordoped) copper chromite.

To activate the alkali decorated copper chromite catalyst, the catalystwas reduced externally (outside the reactor in an external reductionapparatus) in a stream of reducing gas containing H₂. Activation can beperformed with pure hydrogen flowing at 60 cc./min. at 400° C. for 4hours.

Preferably, the alkali or alkaline earth content of the present alkalior alkaline earth promoted catalyst is in the range of approximately 0.3to 50 wt.% based on the weight of the promoted copper chromite. Evenmore preferably, the alkali or alkaline earth content is in the range ofapproximately 5 to 40%. Most preferably, the alkali or alkaline earthcontent is in the range of approximately 5 to 20%.

The present process has several advantages over methanol synthesisprocesses currently in use, including:

1. Methanol can be manufactured by the present process at milderconditions of 100°-160° C. and pressures of 40-65 atmospheres;

2. Up to 95% selectivity to methanol and 90% syngas conversion isobtained, resulting in very low recycle ratios;

3. Alkali or alkaline earth impregnated copper chromite is an effectivemethanol synthesis catalyst;

4. Ethanol is formed at most in trace quantities;

5. High stability and consistent activity are obtained for the catalystwith a low rate of deactivation;

6. CO₂ is a deactivating agent and should be kept as low as possible.However, peak amounts of up to 6% CO₂ may be encountered during processstartup. The catalyst is tolerant to these levels. During operation,however, the CO₂ level falls sharply to around 0.8-1.0%. This level iseasily tolerated;

7. H₂ O is also a deactivating agent and should be kept as low aspossible. The level of water during reaction startup is the highest. Asthe reaction proceeds, however, the level of water drops to reach asteady state concentration of approximately 0.3-0.5% in the liquidphase. This level is easily tolerated by the catalyst;

8. The catalyst system can tolerate fluctuations in the H₂ :CO ratioeffectively;

9. The liquid phase slurry synthesis provides effective temperaturecontrol with rates comparable to processes now operated commerciallyusing copper-zinc oxide catalysts;

10. No soluble salts or organic compounds of alkali or alkaline earthmetals such as the alkoxide need be added to the reactor; and

11. The only major by-products are small amounts of easily separatedmethyl formate and very small amounts of water, carbon dioxide anddimethyl ether.

EXAMPLES Example 1

In Table 1, the reaction rate obtained using the present process iscompared with that obtained with two systems producing methanol via thedirect synthesis. As seen in Table 1, the present process givescomparable rates at a significantly lower temperature. The resultspresented in Table 1 for the present process are for promoted catalystwith 10% K₂ CO₃ loading on copper chromite. The per pass conversion forthis catalyst was 242%.

                  TABLE 1                                                         ______________________________________                                                                 Rate of                                                                       MeOH                                                 Reactor Temp.   Pressure gmol/h/kg                                                                             Other                                        type    (°C.)                                                                          (bar)    cat     conditions                                   ______________________________________                                        Laporte 250     52.12    15.2    CO rich gas                                  Autoclave,                       50001/h/kgcat S.V.                           3 Phase 250     52.12    15.8    Balanced gas                                 slurry                           50001/h/kgcat S.V.                           ICI gas 225     50.0     16.7    Away from                                    phase,                           equilibrium.                                 Fixed Bed                                                                     Present 150     63.0     12.5    H.sub.2 /CO = 2:1                            Synthesis,                       2100 1/h/kgcat S.V.                          slurry                                                                        reactor                                                                       ______________________________________                                    

The advantages provided by the use of an alkali or alkaline earthpromoted copper chromite catalyst are further illustrated by thefollowing examples:

Example 2

Synthesis gas, having an inlet composition of 66.6% H₂ 33.3% CO and 0.1%CO₂ was fed to a 300 cc stainless steel autoclave charged with 6 gm ofcopper chromite (containing 31.1% copper and 29% chromium) impregnatedwith 2% K₂ CO₃ and 150 cc methanol, reduced in situ using a stream ofpure H₂ flowing at 25 cc/min. for 16 hours at 170° C. The catalyst wasadded in the powder form. The reactor was pressurized to 910 psig andthe temperature was adjusted to 150° C. Syngas at a flow rate of 105cc/min. (measured at standard conditions) and a feed H₂ :CO ratio of 2,was made to react with methanol under isothermal conditions. After aninitial transient period, the process reached a steady state withrespect to the amount of synthesis gas converted. A methanol productionrate based on the H₂ consumption of 7.7 gmoles/h/kg. cat was obtainedwith 46% synthesis gas conversion and 95% selectivity towards methanol.An exit gas composition of 62% H₂, 36% CO, 0.8% CO₂, 0.7% methanol, 0.4%methyl formate, 0.2% H₂ O and 0.07% dimethyl ether was obtained. Aliquid composition of 95.6% methanol, 4% methyl formate, 0.3% H₂ O andtraces of dimethyl ether and dissolved gases was obtained. No higheralcohols were detected.

Example 3

Synthesis gas having an inlet composition of 66.6% H₂, 33.3% CO and 0.1%CO₂ was fed to a 300 cc stainless steel autoclave charged with 3 gm ofactivated copper chromite (containing 31.1% copper and 29% chromium)impregnated with 10% K₂ CO₃ and 150 cc methanol and then reduced in situusing a stream of pure H₂ flowing at 25 cc/min. for 16 hours at 170° C.The catalyst was added as a powder. The reactor was pressurized to 910psig and the temperature was adjusted to 150° C. Synthesis gas at a flowrate of 105 cc/min. (measured under standard conditions) was made toreact under isothermal conditions. After an initial transient period,the process reached a steady state with respect to the amount ofsynthesis gas converted. A methanol production rate based on an H₂consumption of 12.5 gmols/h/kg. cat was obtained with 42% synthesis gasconversion and 95% selectivity towards methanol. An exit gas compositionof 65.5% H₂, 32.7% CO, 0.3% CO₂, 0.7% methanol, 0.6% methyl formate,0.2% H₂ O and 0.07% dimethyl ether was obtained. A liquid composition of95.6% methanol, 4% methyl formate, 0.3% H₂ O and traces of dimethylether and dissolved gases was obtained. No higher alcohols weredetected.

Example 4

Synthesis gas having an inlet composition of 66.6% H₂, 33.3% CO and 0.1%CO₂ was fed to a 300 cc stainless steel autoclave charged with 3 gm ofunactivated copper chromite (containing 31.1% copper and 29% chromium)impregnated with 1% Cs₂ CO₃ and 150 cc methanol and then reduced in situusing a stream of pure H₂ flowing at 25 cc/min. for 16 hours at 170° C.The catalyst was added as powder. The reactor was pressurized to 910psig and the temperature was adjusted to 150° C., using a temperaturecontroller. Synthesis gas at a flow rate of 105 cc/min. (measured understandard conditions) was made to react under isothermal conditions.After an initial transient period, the process reached a steady statewith respect to the amount of synthesis gas converted. A methanolproduction rate based on H₂ consumption of 4.92 gmoles/h/kg. cat wasobtained with 23% synthesis gas conversion and 95% selectivity towardsmethanol. An exit gas composition of 65% H₂, 32% CO, 0.8% CO₂, 0.7%methanol, 0.4% methyl formate, 0.2% H₂ O and 0.07% dimethyl ether wasobtained. A liquid composition of 95.6% methanol, 4% methyl formate,0.3% H₂ O and traces of dimethyl ether and dissolved gasses wasobtained. No higher alcohols were detected.

Example 5

To study the effect of CO₂ during the initial transient period,synthesis gas was introduced into the prereduced charge into thereactor, as described in Example 3. The CO₂ content of the feed gas was0.1%. As the reaction progressed, the CO₂ content of the exit gasclimbed steadily to a maximum concentration of approximately 1.2% afterfour hours. The rate of reaction was a minimum at this maximum CO₂concentration. The CO₂ concentration slowly stabilized to reach asteady-state composition of 0.3% in the exit gas. As the CO₂concentration decreased, the rate of reaction increased, climbing to amaximum at around 35 hours. The process is thus tolerant to fluctuationsin the CO₂ level and the possible poisoning effect is reversible. Theprocess has the ability to stabilize the level of CO₂ in the reactionmixture.

Example 6

Synthesis gas having an inlet composition of 66.6% H₂, 33.3% CO and 0.1%CO₂ was fed to a 300 cc. stainless steel autoclave charged with 3 gms.of activated copper chromite (containing 31.1% copper and 29% chromium)impregnated with 1% Ca-nitrate-tetrahydrate and 150 cc. methanol andthen reduced in situ using a stream of pure H₂ flowing at 25 cc/min. for16 hrs. at 170° C. The catalyst was added as a powder. The reactor waspressurized to 910 psig. and the temperature was adjusted to 150° C.Synthesis gas at a flow rate of 105 cc/min. (measured under standardconditions) was made to react under isothermal conditions. After aninitial transient period, the process reached a steady state withrespect to the amount of synthesis gas converted. A methanol productionrate based on the H₂ consumption of 3.2 gmole/h/kg. cat was obtainedwith 11% synthesis gas conversion and 95% selectivity towards methanol.An exit gas composition of 68.0% H₂, 30.0% CO, 0.4% CO₂, 0.8% methanol,0.7% methyl formate, 0.1% H₂ O and 0.05% dimethyl ether was obtained. Aliquid composition of 95.6% methanol, 4% methyl formate, 0.3% water andtraces of dimethyl ether and dissolved gases was obtained. No higheralcohols were detected.

Example 7

Synthesis gas having an inlet composition of 66.6% H₂, 33.3% CO and 0.1%CO₂ was fed to a 300 cc. stainless steel autoclave charged with 3 gms.of activated 10% potassium promoted copper-chromite (containing 31.1%copper and 29% chromium) and 150 cc. methanol. The catalyst was added asa powder. It was then reduced in situ using a stream of pure H₂ flowingat 25 cc/min. for 16 hours at 170° C. The reactor was pressurized to 910psig. and the temperature was adjusted to 150° C. Synthesis gas at aflow rate of 45 cc/min. (measured under standard conditions) was made toreact under isothermal conditions. After an initial transient period,the process reached a steady state with respect to the amount ofsynthesis gas converted. A methanol production rate based on H₂consumption of 11.5 gmoles/h/kg. cat. was obtained with 91.5% synthesisgas conversion and 95% selectivity towards methanol. An exit gascomposition of 58.15% H₂, 35% CO, 1.35% CO₂, 3.0% methanol, 2.3% methylformate, 0.16% H₂ O and 0.01% dimethyl ether was obtained. A liquidcomposition of 95.6% methanol, 4% methyl formate, 0.3% water and tracesof dimethyl ether and dissolved gases was obtained.

Although the invention has been described in detail for purposes ofillustration, it is to be understood that such detail is solely for thatpurpose and that variations can be made therein by those skilled in theart with departing from the spirit and scope of the invention except asit may be limited by the claims.

What is claimed is:
 1. A process for the slurry synthesis of methanolfrom a gaseous mixture comprising carbon monoxide and hydrogen, theprocess comprising the step of the adding a copper chromite upon whichthere has been impregnated and reduced a material selected from thegroup consisting of basic alkali or alkaline earth compounds to a liquidcarrier alcohol in an amount effective to promote the synthesis ofmethanol via a carbonylation/hydrogenolysis concurrent synthesis, inwhich the carrier alcohol undergoes a carbonylation reaction to yield acorresponding alkyl formate and the alkyl formate undergoeshydrogenation to yield methanol and the carrier alcohol, thecarbonylation/hydrogenation concurrent synthesis occurring in a singlereaction vessel at a reaction temperature in the range of approximately100° C. to 160° C.
 2. The process of claim 1 wherein the alkali isselected from a group consisting of lithium, sodium, potassium, rubidiumand cesium.
 3. The process of claim 1 wherein the alkali is selectedfrom a group consisting of sodium, potassium, rubidium and cesium. 4.The process of claim 1 wherein the copper content of the copper chromiteis in the range of approximately 30 to 60 wt.%, based on the weight ofcopper chromite.
 5. The process of claim 1 wherein the chromium contentof the copper chromite is in the range of approximately 40 to 60 wt.%,based on the weight of copper chromite.
 6. The process of claim 1wherein the alkali promoter is present in the range of approximately 0.3to 50 wt.% based upon the weight of promoted copper chromite.
 7. Theprocess of claim 1 wherein the alkali promoter is present in the rangeof approximately 5 to 40 wt.% based upon the weight of promoted copperchromite.
 8. The process of claim 1 wherein the alkali promoter ispresent in the range of approximately 5 to 20 wt.% based upon the weightof promoted copper chromite.
 9. The process of claim 2 wherein thealkali is provided by a compound selected from a group consisting ofoxides, nitrates, hydroxides, carbonates, bicarbonates, formates,citrates, oxalates, acetates, chromates and butyrates.
 10. The processof claim 2 wherein the alkali is provided by a compound selected from agroup consisting of carbonates and nitrates.
 11. The process of claim 1wherein the alkaline earth is selected from the group consisting ofmagnesium, calcium, strontium and barium.
 12. The process of claim 1wherein the alkaline earth metal is selected from the group consistingof calcium and barium.
 13. The process of claim 1 wherein the alkalineearth promoter is present in the range of approximately 0.3 to 50 wt.%based upon the weight of promoted copper chromite.
 14. The process ofclaim 1 wherein the alkaline earth promoter is present in the range ofapproximately 5 to 40 wt.% based upon the weight of promoted copperchromite.
 15. The process of claim 1 wherein the alkaline earth promoteris present in the range of approximately 5 to 20 wt.% based upon theweight of promoted copper chromite.
 16. The process of claim 11 whereinthe alkaline earth is provided by a compound selected from a groupconsisting of oxides, nitrates, hydroxides, carbonates, bicarbonates,formates, citrates, oxalates, acetates, chromates and butyrates.
 17. Theprocess of claim 11 wherein the alkaline earth is provided by a compoundselected from a group consisting of carbonates and nitrates.
 18. Theprocess of claim 1 wherein the synthesis is conducted at a pressurebetween about 40 and 65 atmospheres.
 19. The process according to claim1 wherein the carrier alcohol is methanol.
 20. The process of claim 1wherein a per pass conversion of at least 90% is achieved.